SYMP 15-1 - Understanding the ecology and evolution of insect-specifc viruses: What do we still need to know?

Friday, August 16, 2019: 8:00 AM
Ballroom D, Kentucky International Convention Center
Albert J. Auguste, Department of Entomology, Virginia Tech, VA
Background/Question/Methods

Although insect-specific flaviviruses are abundant in nature, very little is known about their ecological niche, their place in the evolutionary history of flaviviruses, the genetic determinants that render them unable to replicate in vertebrate cells, or to what extent they affect transmission of vertebrate-pathogenic flaviviruses in nature. These viruses represent an unutilized resource that can have enormous ramifications on vertebrate-pathogenic flaviviruses transmission and may be used to protect public health. However, there is a significant bottleneck in scientific research aimed at understanding the mechanisms underlying their super-infection exclusion potential and host-restriction.

Results/Conclusions

Herein we describe the isolation and characterization of a novel insect-specific flavivirus (tentatively named Aripo virus; ARPV) that was isolated from a pool of Psorophora albipes mosquitoes collected in Trinidad. The complete ARPV genome was determined via illumina next generation sequencing and phylogenetic analyses showed that ARPV clusters together with other insect-specific flaviviruses that fall within the pathogenic mosquito-borne clade. ARPV was able to replicate efficiently in cell cultures from five mosquito genera, but did not replicate in other insect or vertebrate cells. Experimentally, ARPV infection is also efficiently transmitted vertically in Aedes aegypti mosquitoes, at least to the F3 generation, where transmission rates then decline dramatically. ARPV antigen was significantly cross-reactive with Japanese encephalitis virus serogroup antisera by both immunofluorescence and hemagglutination inhibition assays, suggesting it may offer cross protection against pathogenic flaviviruses. We also show using transmission electron microscopy of ultrathin sections and immunogold staining that ARPV can attach and enter vertebrate cells via clathrin mediated endocytosis, and the presence of dsRNA replication intermediates in various vertebrate cell types. Subsequent studies showed that infection with ARPV reduces superinfection rates and prevents transmission of West Nile virus (WNV) in Ae. aegypti mosquitoes, by preventing dissemination of WNV to the salivary glands. There was also evidence that ARPV cross-protects from a lethal challenge of WNV in CD1 mice. Herein, I will present the ecological and epidemiological implications of this and related viruses with similar characteristics.